Search results for "electronics"
showing 10 items of 4340 documents
Design and Study of a Wide-Band Printed Circuit Board Near-Field Probe
2021
Magnetic near-field probes (NFP) represent a suitable tool to measure the magnetic field level from a small electromagnetic interference (EMI) source. This kind of antenna is useful as a magnetic field probe for pre-compliance EMC measurements or debugging tasks since the user can scan a printed circuit board (PCB) looking for locations with strong magnetic fields. When a strong H-field point is found, the designer should check the PCB layout and components placement in that area to detect if this could result in an EMI source. This contribution focuses on analyzing the performance of an easy to build and low-cost H-field NFP designed and manufactured using a standard PCB stack-up. Thereby,…
Gigahertz Single-Electron Pumping Mediated by Parasitic States
2018
In quantum metrology, semiconductor single-electron pumps are used to generate accurate electric currents with the ultimate goal of implementing the emerging quantum standard of the ampere. Pumps based on electrostatically defined tunable quantum dots (QDs) have thus far shown the most promising performance in combining fast and accurate charge transfer. However, at frequencies exceeding approximately 1 GHz, the accuracy typically decreases. Recently, hybrid pumps based on QDs coupled to trap states have led to increased transfer rates due to tighter electrostatic confinement. Here, we operate a hybrid electron pump in silicon obtained by coupling a QD to multiple parasitic states, and achi…
Location of holes in silicon-rich oxide as memory states
2002
The induced changes of the flatband voltage by the location of holes in a silicon-rich oxide (SRO) film sandwiched between two thin SiO 2 layers [used as gate dielectric in a metal-oxide-semiconductor (MOS) capacitor] can be used as the two states of a memory cell. The principle of operation is based on holes permanently trapped in the SRO layer and reversibly moved up and down, close to the metal and the semiconductor, in order to obtain the two logic states of the memory. The concept has been verified by suitable experiments on MOS structures. The device exhibits an excellent endurance behavior and, due to the low mobility of the holes at low field in the SRO layer, a much longer refresh …
Impedance of space-charge-limited currents in organic light-emitting diodes with double injection and strong recombination
2006
The impedance model for a one-carrier space-charge-limited (SCL) current has been applied to explain some experimental features of double carrier organic light-emitting diodes. We report the analytical model of impedance of bipolar drift transport in SCL regime in the limit of infinite recombination. In this limit the ac impedance function is identical to that of a single carrier device, with a transit time modified by the sum of mobilities for electrons and holes, μn+μp. The static capacitance C(ω→0) is a factor of ¾ lower than the geometric capacitance, as observed for single carrier devices, but it is shifted to higher frequencies. It follows that impedance measurements in the dual-carri…
Temperature Dependent Quantum Efficiencies in Multicrystalline Silicon Solar Cells
2015
Abstract Several field studies comparing modules based on Elkem Solar Silicon ® (ESS ® ) cells with reference modules based on non-compensated virgin polysilicon show that the compensated ESS ® modules outperform the reference modules with comparable installed capacity under certain operating conditions. At high temperatures and high irradiation conditions the modules based on compensated silicon produce more energy than the reference modules. In order to increase the understanding of the observed effect cells are studied at different temperatures by the means of IV-characteristics as well as quantum efficiencies. Quantum efficiency measurements show that the main difference between ESS ® c…
Si Donor Incorporation in GaN Nanowires
2015
With increasing interest in GaN based devices, the control and evaluation of doping are becoming more and more important. We have studied the structural and electrical properties of a series of Si-doped GaN nanowires (NWs) grown by molecular beam epitaxy (MBE) with a typical dimension of 2-3 μm in length and 20-200 nm in radius. In particular, high resolution energy dispersive X-ray spectroscopy (EDX) has illustrated a higher Si incorporation in NWs than that in two-dimensional (2D) layers and Si segregation at the edge of the NW with the highest doping. Moreover, direct transport measurements on single NWs have shown a controlled doping with resistivity from 10(2) to 10(-3) Ω·cm, and a car…
Acoustic manipulation of electron-hole pairs in GaAs at room temperature
2004
We demonstrate the optically detected long-range (>100 μm) ambipolar transport of photogenerated electrons and holes at room temperature by surface acoustic waves (SAWs) in (In,Ga)As-based quantum well structures coupled to an optical microcavity. We also show the control of the propagation direction of the carriers by a switch composed of orthogonal SAW beams, which can be used as a basic control gate for information processing based on ambipolar transport.
Surface Coatings Based on Polysilsesquioxanes: Solution-Processible Smooth Hole-Injection Layers for Optoelectronic Applications
2009
Optoelectronic devices usually consist of a transparent conductive oxide (TCO) as one electrode. Interfacial engineering between the TCO electrode and the overlying organic layers is an important method for tuning device performance. We introduce poly(methylsilsesquioxane)-poly(N,N-di-4-methylphenylamino styrene) (PMSSQ-PTPA) as a potential hole-injection layer forming material. Spin-coating and thermally induced crosslinking resulted in an effective planarization of the anode interface. HOMO level (-5.6 eV) and hole mobility (1 × 10(-6) cm(2) · Vs(-1) ) of the film on ITO substrates were measured by cyclovoltammetry and time-of-flight measurement demonstrating the hole injection capabili…
From monolayer to multilayer N-channel polymeric field-effect transistors with precise conformational order
2012
Monolayer field-effect transistors based on a high-mobility n-type polymer are demonstrated. The accurate control of the long-range order by Langmuir-Schafer (LS) deposition yields dense polymer packing exhibiting good injection properties, relevant current on/off ratio and carrier mobility in a staggered configuration. Layer-by-layer LS film transistors of increasing thickness are fabricated and their performance compared to those of spin-coated films.
Tunable field effect properties in solid state and flexible graphene electronics on composite high – low k dielectric
2016
We demonstrate tunable field effect properties in solid state and flexible graphene field effect devices (FEDs) fabricated using a poly(methylmethacrylate) (PMMA) and lithium fluoride (LiF) composite dielectric. Increasing the concentration of LiF in the composite dielectric increases the capacitance, which thereby reduces the operating gate voltages of FEDs significantly from 10 V to 1 V to achieve similar conductivity. Electron and hole mobility of 350 and 310 cm2/V at VD = −5 V are obtained for graphene FEDs with 10% LiF concentration in the composite. Composite dielectric also enabled excellent FEDs on flexible substrates without any significant change in mobility and resistance. Flexib…